Vardi et al. PCT Patent Application No. PCT/US99/04913, which published on 18 Nov. 1999 as International Publication No. WO 99/58059, discusses an optical-acoustic imaging device. In that document, which is incorporated herein by reference in its entirety, including its disclosure of a guidewire optical-acoustic imaging device, an elongated imaging guidewire includes an elongated optical fiber driven by light from a laser. A distal end of the guidewire includes a polyvinyldiene fluoride (PVDF) film piezoelectric ultrasound transducer. The ultrasound transducer transmits ultrasound to an imaging region of interest about the distal tip of the guidewire, and also receives the returned ultrasound energy. The received ultrasound energy deforms a Fiber Bragg Grating (FBG or “Bragg grating”) at the distal end of the guide wire, which, in turn, modulates the optical signal through the optical fiber. Imaging information about the region of interest is then obtained at the proximal end of the guidewire from the modulated optical signal.
Among other things, the present applicant has recognized that a piezoelectric ultrasound transducer may be difficult to integrate with a minimally-invasive guidewire because of electrical signal losses in ultrafine electrical conductors extending longitudinally through the guidewire assembly. Moreover, the present applicant has recognized that the field of view of the Vardi et al. device may be limited by the size of aperatures around the PVDF ultrasound transducers and/or the spacing between FBGs. Furthermore, the present applicant has recognized that the sensitivity of the Vardi et al, device may limit its usefulness in an imaging application. For these and other reasons, the present applicant has recognized that there is an unmet need in the art for improved systems and methods for performing optical-acoustic imaging.